1. Field of the Invention
The invention relates in general to light guides and more particularly to a spring-type mounting feature for securing a light guide in a vehicle instrument cluster behind a dial or appliqué.
2. Discussion of Related Art
Some prior lamp assemblies for mounting in vehicles used flexible supports designed to prevent damage to light bulb filaments caused by vibratory forces. In U.S. Pat. No. 3,327,110, for example, a bulb socket for a head lamp was suspended within a reflector member behind a lens by a pair of resilient arms. The arms were meant to allow for some displacement of the socket in various directions for the purpose of absorbing and reducing shock forces on filaments of a bulb received in the socket.
Typical instrument cluster assemblies, such as the one disclosed in U.S. Pat. No. 6,409,355, include a series of light emitting diodes (LEDs) arranged on a printed circuit board (PCB). The LEDs are covered by light passages extending through a housing mounted directly on the PCB. The housing is positioned behind a cutout in an optical conductor plate mounted directly behind an appliqué or dial to project additional, backlit information from the PCB onto the dial. The dial, conductor plate, light guide and PCB are sandwiched together between an instrument cluster frame or mask and a rear wall or cover.
In some instrument cluster assemblies, a near perfect fit of the separate parts is required to avoid leakage of light intended only for one dial or appliqué into other areas and displays of the cluster, and to prevent rattle noise within the assembly. This type of close fit can be difficult to achieve. There are also constraints on the assembly process. For example, adhesive use is generally prohibited. There is usually an assembly order wherein the appliqué is placed over the rear opening of the mask. Then the light guide, printed circuit boards and rear cover are assembled in that order. Any improved assembly structure must take into account these constraints without adding costly additional steps to the process.